Dublin Airport 6 Bay Extension

The Six-Bay extension to Terminal 1 at Dublin Airport, completed in 2002, doubled the passenger capacity of Dublin Airport to close to 20 million per annum, allowing future growth in numbers for many years to come.

The construction works for the terminal building commenced in June 1998 and were successfully completed on programme, on 28th February 2002. The entire project was carried out in a number of phases to allow the massive construction programme to progress, whilst at the same time, allowing the Airport to function in a safe and effective manner. The project can directly be split into the following main areas: New Basement, New 6-Bay Extension and Refurbishment of existing 8-Bay Terminal.

The construction of the new basement at the time presented significant engineering challenges, due to its depth and proximity to the existing buildings. The basement single- storey double height space was 9m deep, requiring a variety of complex temporary works solutions. A combination of soil nailing, contiguous piled wall, underpinning and safe slope stability, was employed depending on the position relative to surrounding areas.

Due to the large superstructure grid arrangement (22m x 12.2m) and the requirement to minimise the basement foundation / slab in between, ground anchors were incorporated to resist hydrostatic uplift. The basement was waterproofed using a preprufe membrane to allow for future flexible occupation. The logistics required to remove the 60,000m3 of excavated material from site via designated routes across the apron and airfield, as well as bringing and placing the concrete, were extremely involved.

The 6-Bay terminal extension comprising a steel frame structure at a grid of 22m x 12.2m, gave both significant design and construction challenges. The decision was taken to maintain the same floor-to-floor heights as the existing 8- Bay building with increased headroom. This was achieved by a series of primary and secondary steel, 1.6m deep, Warren-Type trusses acting compositely with P.C. hollowcore and structural screed, spanning 6.1m.

It was particularly critical to integrate significant services ducts through the warren trusses. A site test was conducted to assess the dynamic performance of the long spanning trusses and found to perform well within acceptable criteria (5Hz). The 4,000 tonne steel frame and 22,500m² of P.C. units was erected in a 16 week period by working 24-hour shifts with steelwork mainly during the day (delivered at night) and P.C. units at night.

The refurbishment of the existing terminal required extensive structural investigation as significant interventions were made on the structure. Impact on passenger movement was kept to a minimum. Alteration works requiring steel 914 UB’s to be transported across the departures floor and lifted into position, were generally carried out at night.